With adapted formulations, process and plant layout modifications Indigo, VAT, Reactive, Sulfur, Direct and Pigment dyes will be applied and fixed continuously on Cellulosic / Lyocell warp yarn and fabric by use of the patented RotoDyer spray dyeing (forced application).
The non-contact spray application also allows the defined application of high affinity optical brighteners, fixing agents, functional chemicals, special neutralization agents and oxidation chemicals. A significant reduction of CO2 emission is measured. The marketing story of sustainability is getting reality.
The standard Indigo warp yarn spray process uses HydroBlue®90 as the reducing agent. Selected special auxiliaries avoid the formation of vat skin and protect the reducing agent and the Indigo dye from oxygen in the air. Conceptions by using steaming in combination with classical airing increases the flexibility of spray units.
The newly developed PS2 Pad-Spray-Steam Process for yarn and fabric enables a low-salt continuous dyeing of Reactive dyes without limitation of colour depth. The diffusion behaviour of the dyes is comparable with Cold Pad Batch dyed material. Intermediate drying as normally used in classical pad-dry-chemical pad-steam process is eliminated. This will lead to significant energy savings and much lower investment costs as well.
Revolution in VAT and REACTIVE dyeing on woven fabric
PS2 Pad-Spray-Steam Process has started successfully in February 2019 in Lahore/Pakistan at Nishat Mills with outstanding results. Meanwhile around 5 million meters are produced with significant savings of chemicals as well as significant reduction of salt and CO2 emissions.
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In addition a new to bath or one-bath Pigment dyeing method using pigment preparations, combined with a auxiliary package, is developed for Denim with great feedback in the Denim industry as well as at the retailers by promoting a sustainable ‘low-water dyeing’ method for warp yarn
A pre-reduced liquid Sulfur dye range with minimal sulfide content from Archroma in combination with advanced spray dyeing is successfully used for warp yarn with significant advantages in water saving.
Patented RotoDyer spray application
For functionalization minimum application (MA) on fabric, approximately 12% – 35% pick-up is very often applied on face side only. For warp yarn dyeing/finishing a pick-up of 50- 70% ore even more can be easily realized. New Bio-Polymers are in R&D for spray sizing as well.
Spray dyeing is a disruptive technology and will replace long-established systems. It shows highest possible flexibility with small lot sizes. The non-contact spray application prevents dirt, fluff, grease, waxes, residual surfactants or alkali from being dragged into the spray solution. Yarn or fabric is not subject to mechanical stress from crushing and thus no change in the capillary structure will take place. The RotoDyer spray technology supports “zero-discharge” concepts (e.g., INDIGO filtration / recycling), is economical and sustainable (BAT candidate). The space requirement and the investment cost for warp dyeing equipment is drastically reduced.
All common classes of dyes for Cellulose / Lyocell fibers can be applied without contact and there are completely new combination possibilities.